Can/ you/ sign an autograph? - No
Can you sign an autograph? - No, I can't.
Can/ I/ lunch? - No
Can I have lunch? - No, you can't.
May/ I/ talk to fans? (No)
May I talk to fans? - No, you may not.
Can/ they/ do an interview? - No
Can they do an interview? - No, they can't.
May/ he/give a concert? - Yes
May he give a concert? - Yes, he may.
May/ he/give a concert? - No
May he give a concert? - No, he may not.
May/ I/ talk to fans? (Yes)
May I talk to fans? - Yes, you may
Can/ they/ do an interview? - Yes
Can they do an interview? - Yes, they can.